Kerala Health Minister Veena George today said that 251 persons, including 129 health workers have been traced to have to come into contact with the boy, who lost his life to Nipah virus in Kozhikode on Sunday.
Of these, 54 are in the high risk group.
Addressing a press conference in Kozhikode this evening, Ms George said, 11 persons in the contact list have developed symptoms of the infection, but their condition is stable.
The result of eight samples sent to the National Institute of Virology in Pune is expected tonight.
She said, the lab set up by the National Institute of Virology, Pune at the Kozhikode Medical College Hospital became functional this evening.
Fruits, bat droppings and other animal samples have been collected from the region where the infection was first detected.
An expert team from the National Institute of High Security Animal Diseases, Bhopal will be reaching Kozhikode on Wednesday.
The Minister said, though the situation is not alarming, vigil should be maintained.